This project investigates the epidermal-lamina poropria junction, knwon as the basement membrane zone (BMZ). The basic questions are, "What holds the epidermis to the fibrous structures of the lamina propria?" and "Why is BMZ pathology so frequent in benign laryngeal disease?" Histology of human vocal nodules and Reinke's edema suggests the BMZ plays an important role in vocal injury. The BMZ in skin is composed of attaching stuctures, such as hemidesmosomes and anchoring fibrils which help secure the lamina propria to the epidermis. The BMZ in skin also contains many proteins which help hold or "glue" the BMZ intact. Through electorn microscopy, morphometric studies will be performed to determine the population density of the attaching BMZ structures in normal human and canine vocal cords. Since dermatiological studies have shown variation in population densities of attaching structures across individuals, the project will determine normal ranges for attaching BMZ structures. Through immunofluorescent, and immunoelectron microscopic techniques, the proteins of the BMZ will be characterized in normal human cords. After normative data has been obtained, it will be used to help determine abnormalities of the BMZ in injured cords. It is suspected that vocal nodules are the result of injury to BMZZ structures. Vocal nodules, polyps or Reinke's edema specimens will be examined to determine if a) certain individuals may inherently have a low number of attaching structures or proteins leading to a lower threshold for phonatory injury and b) chronic injury to these structures lead to biological changes in the BMZ. Additionally, acute canine models of phonatory injury will be examined for BMZ injury. The investigation will identify both the architecture (using electron microscopy) and the biological composition (using immunoflourescence techniques) of the BMZ. Pathogenesis of vocal injury will be studied witb interest towards possible anatomical factors which may impose some vocal cords to injury. It is the long range plan to acquire greater skills in state of the art electron microscopic techniques and immunofluorescent techniques to investigate laryngeal anatomic and biological components. With these skills, benign laryngeal disease causing phonatory dysfunction and therapy will be studied.